In my humble opinion, it should be safe to learn from. Most basic functionality have remained backward compatible - there might, however, be some underlying structures that have changed of the years but simple things like form design, variable declaration etc have remained very much the same since the days of Pascal compilers.

IMHO there are more tutorials for Delphi 7 than the prior versions (and for later version if that matter). There is generally no big problem for using tutorials for earlier versions, except maybe some routines/resources contained in different units or renamed routines/classes or dropped routines/classes.